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material is part of the mill yard area. Cover material will be dozed directly over the disposal site <br />or hauled from the yard area as needed to meet the cover requirements. Since this disposal site <br />(even if not used as such) would be included in recontouring of the mill yard, it will not create <br />any additional acreage of reclamation at the mill. Henderson will cover the 7.5 acre disposal site <br />with at least 36,300 cubic yards of material to create the 3 foot cover. Based upon the present <br />topography of this area, the final reclaimed slopes will be 2.5 W 3:1. While 3:1 or flatter is the <br />goal, the natural topography on the northwest comer of this site is slightly steeper. <br />The proposed smaller site in Area 18 presently is the active non-hazardous waste disposal site <br />for the mill. The 968 cubic yards of material necessary fora 3 foot cover at this site presently is <br />stockpiled directly adjacent to the site. This material was stockpiled when the site was initially <br />excavated. As with the large site in Area 5, this smaller site will be recontoured with slopes <br />between 2.5 to 3:1. <br />4. Material Testing and Burial: By definition, the two mill site repositories can contain <br />only non-hazardous debris determined as such through testing as discussed in TR-12. The <br />location and preparation of these sites are significantly different from the site at the Climax Mine <br />Storke complex referenced in TR-12. The Climax Mine repository included potentially acid <br />generating rock material and utilized a french drain system to route drainage directly to the water <br />treatment collection and pump station located directly adjacent and below the site. Both <br />Henderson mill site repositories will drain directly to the tailings impoundment and will not <br />contain potentially acid generating materials. However, as stated in TR-12, Henderson will <br />incorporate slow-permeability soil into the design of the larger Area 5 site. The small site at <br />Area 18 is the ctttrent landfill and will not be re-excavated given its location directly adjacent to <br />the tailings impoundment. <br />For purposes of the FW recalculation, Henderson is proposing to line the sides and bottom of the <br />larger repository (Area 5; 7.5 acres) with 1 foot of low-permeability soil. The 12,100 cubic <br />yards of soil material to line this site will come from the western perimeter of the tailings <br />impoundment, a haul distance of approximately 5 miles, A review of the U.S Forest Service <br />(USFS) soils survey and map for this area (Collins, T., and G. Rocky. 1969. USFS Hot Sulphur <br />Springs Ranger District, Arapaho National Forest) shows that the entire west perimeter of the <br />tailings impoundment is within Soils #10, and #23. These soils are described as clay loams and <br />silty clays with less than IS percent grnvels and thick B horizons that are `bery sticky and <br />plastic when wet " <br />Soil samples collected from this area by URS, Inc. on November 18, 2002 indicate that these soils <br />meet the requirements for use in the repository. Results of the analyses are attached to this <br />submittal. <br />2 <br />